The present invention relates to a graphic display system which operates at high speed to provide real time display.
Conventional graphic display systems comprise a central processing unit, a frame memory in which display data are stored, a controller that controls the frame memory and a graphic display unit to transfer the stored information from the memory to the display unit by way of a digital-analog converter. The CPU is supplied with various items of prestored information on the location of apexes of solid objects, the luminance and chromatic information of each polygonal surface of the objects and the position of a light source relative to the objects and items of variable information on the angle, position and direction of the point from which the objects are viewed. The CPU is programmed to provide perspective conversion, interconnection between apexes by interpolating the data on the locations of the apexes. These processed data are fed to the frame memory and retrieved therefrom to provide hidden surface processing during display operation. This involves making a decision on which plane or planes are to be hidden behind the desired; the decision is conventionally performed by a series of programmed instructions.
Because of the great number of picture elements for which the hidden surface processing must be performed, it takes a substantial amount of time to complete the display of a whole image, typicaly several minutes to several tens of minutes depending on the amount of information to be processed for each picture element. Therefore, the usual practice involves the use of a recording medium for storing the computed display data at a low speed and playing it back at the speed of a television raster scan speed.